This application relates generally to gas turbine engines and, more particularly, to compressors for gas turbine engine.
Air pollution concerns worldwide have led to stricter emissions standards. These standards regulate the emission of oxides of nitrogen (NOx), unburned hydrocarbons (HC), and carbon monoxide (CO) generated as a result of gas turbine engine operation. In particular, nitrogen oxide is formed within a gas turbine engine as a result of high flame temperatures. Often making modifications to a gas turbine engine in an effort to reduce nitrous oxide emissions has an adverse effect on operating performance levels of the associated gas turbine engine.
Known gas turbine engines often have attempted to reduce nitrous oxide emissions by increasing airflow through the gas turbine engine during operating conditions. Gas turbine engines include preset operating parameters and any such airflow increases are limited by the preset operating parameters including turbine nozzle cooling parameters. As a result, to increase the airflow within the gas turbine engine, the gas turbine engine and associated components should be modified to operate at new operating parameters.
Because such gas turbine engine modifications are labor-intensive and time-consuming, users are often limited to derating the operating power capability of the gas turbine engine and prevented from operating the gas turbine engine at fill capacity. Such derates do not limit an amount of nitrous oxide formed as the engine operates at full capacity, but instead limit the operating capacity of the gas turbine engine.
In an exemplary embodiment, a gas turbine engine includes a compressor rotor assembly which effectively reduces an amount of nitrous oxide emissions formed by a the gas turbine engine. The gas turbine engine includes a combustor operable with a fuel/air mixture equivalence ratio less than one. The compressor assembly includes a first rotor, a second rotor, and a water injection assembly. The water injection assembly is mounted to the gas turbine engine and includes a water delivery system and an air delivery system. The water delivery system includes a plurality of spray nozzles connected to the gas turbine engine to inject water between the first rotor and the second rotor. The air delivery system includes a plurality of piping connected between the water delivery system and the gas turbine engine to supply bleed air to the water injection assembly to atomize the water being supplied to the gas turbine engine.
In operation, compressor bleed air exits a high pressure compressor and atomizes water flowing through the water delivery system. The spray nozzles direct a fine mist downstream towards an inlet of the high pressure compressor. The mist lowers a temperature of the airflow within the gas turbine engine which permits the airflow exiting the high pressure compressor to have an increased heat capacity. The increased heat capacity reduces flame temperatures within the gas turbine engine and as the flame temperatures are reduced, less nitrous oxide emissions are generated. As a result, either nitrous oxide emissions are improved for specified gas turbine engine operating power levels, or the gas turbine engine has an increased operating power level for a specified nitrous oxide emission level.